Red Rock star Denise McCormack has promised things are set to become darker and edgier when the show returns to screens this month.

The series is in for some big changes for its third season. The show has ditched its half-hour episodes twice a week in favour of one hour-long episode each week, marking the show's move from soap to serial drama.

The Drimnagh native is confident fans will respond well to the change.

"It will be edgier and darker but keep the elements of Red Rock that are successful and that the audience love," she told the Herald.

"It's not going to be a Love/Hate. It will be different. It will be something new."

McCormack, who plays Bridget Kiely, is confident the show will get bigger and better as time goes on.

"From the word go we knew we wanted to create something really special, and I think that's a testament to it," she said.

"It has potential to grow bigger and better, and that is what the writers, directors and actors are all looking forward to."

The change in format for the show means it will lose its comparison to long-running RTE soap Fair City, with the shows previously being seen as rivals.

However, the actress insisted Red Rock is now going in a new direction.

"The comparison was that it was a soap on twice a week for a half an hour but now with the change it's going to be an hour, it's going to be post-watershed," she said.

"We'll get away with doing stuff that's a little bit more psychological. We'll look at the characters more in-depth."

Audiences are in for a treat when the show returns with a dramatic opening episode.

Fans last saw crooked cop Brian McGonigle's body wash up on the beach in Red Rock, the victim of a brutal murder.

But with many enemies with plenty of motives, viewers were left trying to solve the mystery of who murdered Brian. Viewers will discover the cop's killer on September 12.